基于液晶构建长程有序非碘电对通道强化染料敏化太阳电池性能

Liquid crystal electrolytes, containing lamellar pathways of thiolate/disulfide redox couples constructed by virtue of the smectic dynamic order, are developed for dye-sensitized solar cells (DSSCs). The effect of the ordered pathways on the photovoltaic properties of DSSCs is investigated. The smectic liquid crystal electrolytes are prepared by synthesizing smectic liquid crystals with thiolate ions and doping the liquid crystals with corresponding disulfides to provide redox couples. The performance of the electrolytes is further optimized by adding additives. The redox couples would aggregate into lamellae between the smectic layers to form two-dimensional pathways, which would facilitate the charge transfer via Grotthuss-typed ion exchange mechanism. The smectic electrolytes are macroscopically aligned by approaches including mechanical shearing, electric field induction and alignment layer induction to construct interconnected lamellar pathways between electrodes of DSSCs. The long-range pathways are excepted to significantly enhance the charge transfer in the electrolytes. The aligned nanostructures are solidified by physical crosslinking or in-situ photopolymerization to prepare anisotropic quasi-solid-state or solid-state electrolytes for promoting the stability of the ordered charge transfer pathways. The photoelectrochemical behavior of the prepared DSSCs is studied using electrochemical technique to reveal the reinforcement mechanism of the ordered nanostructures on the charge transfer in DSSCs. The solid-state electrolytes, firstly prepared from macroscopical alignment and solidification of liquid crystal electrolytes, are looking forword to achieve efficient charge transfer over the limitation of viscosity, which have potential to improve the photovoltaic properties and stability of DSSCs.

本项目利用近晶相液晶的动态有序性，在电解质内构建层状巯基/二硫氧化还原电对通道，探究有序通道对染料敏化太阳电池（DSSC）光电性能的影响。合成近晶相巯基离子液晶，掺杂对应二硫化物组成电对制备近晶相液晶电解质，并利用添加剂优化性能。电对在近晶相分子层间富集形成二维通道，以利于Grotthuss型离子交换电荷传输。利用机械剪切、电场诱导、取向剂取向等方法实现电解质分子的宏观取向，在DSSC电极间构建贯通的长程有序层状电荷传输通道，以期大幅度强化电解质电荷传输性能。通过物理交联、光致原位聚合等手段固化宏观取向结构开发各向异性准固态、固态电解质，提升有序电荷传输通道的稳定性。利用电化学方法研究DSSC的光电化学性能，揭示电解质内有序结构对DSSC电荷传输的强化机制。本项目首次利用近晶相电解质的宏观取向与结构固化开发固态电解质，有望克服黏度限制实现高效的电荷传输，提升DSSC的光电转换性能与稳定性。

传统电解质普遍存在电荷传输高效性与稳定性间的博弈，严重制约高性能源器件的发展，开发高效稳定的新型电解质对于各类能源器件的高性能长期使用意义重大。针对此问题，本项目以染料敏化太阳电池（DSSC）为研究对象，并基于近晶相离子液晶的动态有序性与热稳定性开展电解质研究，主要研究内容包含：1. 近晶相离子液晶电解质的结构设计、可控制备与性能优化，2. 在DSSC器件限域空间内基于离子液晶构筑长程连续通道的手段并解析电荷传输强化过程，3. 在器件内原位固化离子液晶获得高性能纳米结构固态电解质的方法与效果，4. 近晶相结构电解质强化DSSC光电性能和稳定性的效果与机理。取得的主要结果如下：1. 首次提出了聚合物联通离子液晶畴自组装原位构筑长程连续通道强化电解质综合性能的新方法，并基于所得固态电解质制备了光电转换效率8.2%、稳定工作5000h的高性能固态DSSC。上述方法能够不依赖外加手段在能源器件限域空间内自发形成热稳定的电荷传输强化通道，为离子液晶电解质在大尺度能源器件内的高效应用提供了新途径。2. 提出了基于离子液晶原位制备高性能纳米结构全固态电解质的新方法，其优势在于离子液晶的动态结构能够保证电解质的浸润性，而后续原位固化能够保留电解质有序结构获得全固态DSSC。基于上述方法获得了离子传输性能及器件表现均优于离子液晶前体的全固态纳米结构电解质，为解决固态电解质离子传导率低，界面浸润性差等问题提供了新思路与新方法。3. 提出溶致液晶构筑液态通道强化能源器件性能的新方法，利用离子液晶在适量液态电解质内的自组装构筑液态离子传输通道，首次获得了室温离子传输性与长期稳定性均能优于液态电解质的溶致型准固态离子液晶电解质，表明溶致液晶具备成为下一代高性能电解质的潜质。本研究基于离子液晶所构筑的高性能固态电解质，能够有效解决电解质电荷传输效率与稳定性间的博弈问题，为实现能源器件的高效性与稳定性的双赢提供了新方法，具有十分重要的科学意义。